1. Field of the Invention
The present invention relates to a technique of performing remote supervision and diagnosis, by using a mobile program that is transmitted from a central system via, particularly, a network.
2. Description of the Related Art
In recent years, systems have been developed, which are designed to perform remote supervision and diagnosis on an object, such as plant apparatus or an elevator, from a place remote from the object. More specifically, such a system is applied to a power-unit protection and control system that is configured to achieve remote protection and remote-control of, for example, a power system. Refer to, for example, the following Documents 1 to 3:    1. Ryouichi Tsukui, Fumio Matsuda and Kuniaki Suzuki, Power-System Supervision and Protection System in a Change, Toshiba Review, Vol. 54, No. 6, pp. 26-29, 1999    2. Yoshiaki Hasegawa, Yoshio Ebata and Hideki Hayashi, Power-System Supervision and Control System for Use in Combination with the Intranet, Toshiba Review, Vol. 54, No. 6, pp. 30-33, 1999    3. Katsuhiko Sekiguchi, Shoji Takenaka and Yoshihiro Shirota, Application of the Intranet Technology to Power-System Protection and Control System, Toshiba Review, Vol. 54, No. 6, pp. 34-37, 1999
A plant supervision and diagnosis system designed to perform remote supervision and diagnosis of a plant has been proposed (see, for example, Japanese Patent No. 3621935.) This system performs a supervision/diagnosis process and a plant control process, by executing a plant control program and a plant supervision/diagnosis program in cooperation. Further, a system that supervises, diagnoses, inspects and maintains a plurality of power plants from a remote site has been proposed (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2003-114294). This system is designed for plants such as power system and configured to utilize an intranet.
That is, various types of remote supervision and diagnosis systems have been developed or proposed, such as systems for supervision only, systems for diagnosis only, systems for supervising and diagnosing tens of thousands of objects, systems for supervising and diagnosing objects each having a various process functions, and systems using the Internet connected to the public line. Particularly in recent years, attention is paid to remote supervision and diagnosis systems using mobile agent technology (see, for example, Jpn. Pat. Appln. KOKAI Publications Nos. 2006-280198, 2004-70428, 2002-297557 and 2000-134786).
In most remote supervision and diagnosis systems, a network connects the remote objects and the central system (central supervision system). Due to a disaster, the network may fail to connect the remote objects and the central system. Measures must be taken to guard the system against disasters. To this end, it has hitherto been proposed that data be backed up, that servers be backed up or recovered (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-171506).
As stated above, some measures must be taken to guard the system against disasters, preventing the disconnection of the remote sites from the network in the event of a disaster. No prior art that can effectively guard the system is available, however. Once the network has failed to connect the remote objects and the central system, there is no other way than supervising and diagnosing the objects directly, one by one, employing maintenance personnel, and then utilizing the results of the supervision and diagnosis.
An enormous load is imposed on the maintenance staff member who collects maintenance information required for supervising and diagnosing the objects, in order to investigate the conditions of the objects during or immediately after a disaster, such as disconnection of the remote sites from the network. In view of this, the method of supervising and diagnosing the objects directly is not always effective to guard the system against disasters.